I've been practicing this concerto, and I've had a hard time finding places to breath in the tempo change at the beginning. The edition I have doesn't have suggested breathing places or anything really, so it's hard to find good places to breath. The biggest issue is right before the low Cs 3 and 4 bars after the tempo change, or bars 22 and 23.

You'll have to sneak some breaths, after getting a nice big one on maybe count 3 of measure 21. It helps to start with a good breath in a phrase like that. I would probably try to sneak them before the and of 4 in 22 and in a similar place in 24.

It'll help to be really efficient with the low Cs and probably not playing too loud in general.